PJB-2019-1008
A tomato mutant (hair) with a novel type of trichomes confers resistance to tomato yellow leaf curl virus (TYLCV) transmitted by whiteflies (Bemisia tabaci)
Yunzhou LI
Abstract
The tomato yellow leaf curl virus (TYLCV) is recognized as a serious pathogen of tomato. It is critical to find novel sources of resistance to reduce yield losses caused by TYLCV. The virus is mainly transmitted leaf-to-leaf by whiteflies (Bemisia tabaci). A tomato mutant (hair) with a novel, branched trichome type, which resulted from mutations with ethyl methane sulphonate (EMS), was regarded as a potential germplasm resource, because of its excellent performance on resistance/toterance to insects. In the present study, the trichomes of hair tomato mutants and WT plants were subjected to deepening analyses. Four trichome types (Type I, Type III, Type V and Type VI) were found in the WT plants, while, the hair mutant only had type VI and branched trichomes. More importantly, type VI was not branched in hair mutant plants, which suggest that the control gene for branching of type VI trichomes is different from that of Type I, Type III and Type V. In addition, the susceptibility of Begomovirus to TYLCV was evaluated in hair and WT plants by polymerase chain reaction (PCR) and Enzyme Linked Immunosorbent Assay (ELISA). A whitefly (Bemisia tabaci)-transmission test was conducted for further verification of virus infection. The results indicated that TYLCV could infect hair mutants, but its accumulation in inoculated leaves was much lower than in the resistant tomato material of “Y19” (with Ty-1 and Ty-3), the susceptible tomato line M82 and the WT. Moreover, no TYLCV particles could be detected in new leaves of inoculated hair mutants. Genetic investigation revealed that the mutation was monogenic and the allele for branched trichomes was recessive. Four yield traits were tested, including the percentage of setting fruit (%), that was not significantly different between hair and WT plants. In this study, we provide the first evidence that the hair mutant is highly tolerant to TYLCV and possibly has a negative effect on the virus transmission by whiteflies from affected leaves to new leaves via branched trichomes on the epidermis.
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